1. Field of the Invention
This invention relates generally to optical and magneto-optical data storage systems, and in particular to a thin film electro-magnetic coil assembly for use in optical and magneto-optical data storage systems. The coil assembly may be used in other applications, including but not limited to wireless telecommunications, sensors, transducers, transformers, and inductors.
2. Description of Related Art
A conventional magnetic storage system includes a magnetic head that has a slider element and a magnetic read/write element, and is coupled to a rotary actuator magnet and a voice coil assembly by a suspension and an actuator arm to be positioned over a surface of a spinning magnetic disk. In operation, lift forces are generated by aerodynamic interactions between the magnetic head and the spinning magnetic disk. The lift forces are opposed by equal and opposite spring forces applied by the suspension such that a predetermined flying height is maintained over a full radial stroke of the rotary actuator assembly above the surface of the spinning magnetic disk.
Flying head designs have been proposed for use with optical and magneto-optical (MO) storage technology. One motivation for using the magneto-optical technology stems from the availability of a higher areal density with magneto-optical storage disks than magnetic storage disks. However, despite the historically higher areal storage density available for use with magneto-optical disks drives, the prior art magneto-optical disk drive volumetric storage capacity has generally not kept pace with the volumetric storage capacity of magnetic disk drives.
One factor that limits MO disk drives is the magnetic coil that generates the necessary magnetic field for writing data on the MO disk. The magnetic field is applied to a spot of interest on the MO disk from the direction of the incident laser beam, or from the opposite direction. However, the magnetic coils used in these commercial magneto-optical heads are relatively large and heavy device with bulky hand wound coils. These large magnetic coils generally have high inductance and low resonance frequencies leading to background noise problems at higher data transfer rates.
The following patents provide examples of electro-magnetic coil designs for use in MO heads:
U.S. Pat. No. 5,105,408 issued to Lee et al.; PA1 U.S. Pat. No. 5,295,122 issued to Murakami et al.; and PA1 U.S. Pat. No. 5,563,871 issued to Bargerhuff et al.
What is needed is an electro-magnetic coil assembly that is small, with a low mass, and that is capable of generating a vertical magnetic field intensity greater than 200 Oersteds over a large area. The electro-magnetic coil assembly allows high data transfer rates from an optical or a MO data storage system.